1. Field of the Invention
The present invention generally relates to a rotary connector to be used as an electrical connection means for an airbag system and so on. More particularly, the present invention relates to a rotary connector of the type that leads a flat cable accommodated in a space defined between a pair of housings to the exterior through a lead block.
2. Description of the Related Art
A rotary connector broadly comprises a pair of housings connected in such a way as to be concentric with and rotatable with respect to each other and a flat cable accommodated in a space defined between these housings. The ends of flat cable respectively fixed to these housings are electrically led to the exterior of the space. One of the housings is used as a stationary member, while the other is used as a movable member. When the movable housing is rotated clockwise or counterclockwise with respect to the stationary housing, the flat cable is wound or unwound in the space.
The rotary connector broadly configured in this manner is used as an electrical connection means for an airbag system and a horn circuit by respectively attaching the stationary housing and the movable housing to a stator member, such as a steering column, and a steering wheel acting as a rotor member. At that time, both the ends of the flat cable need to be connected to the stator member and an electric component mounted on the steering wheel. A rotary connector disclosed in the Japanese Utility Model Publication No. 4-24611 Official Gazette is configured so that both the ends of the flat cable are electrically led to the exterior through a lead block fixed to the housings. This lead block has a plurality of joint bars supported by insulating members. The lead block and the flat cable are accurately positioned in the connector. In this state, each of the joint bars is ultrasonically welded to a corresponding conductor. Then, the lead block is fixed at a predetermined place in the housing.
Meanwhile, in recent years, there have been demands for increasing the number of electrical circuits to be connected by a rotary connector. A rotary connector adapted to accommodate two flat cables in the space defined between the housings as described in the European Patent Application Publication No. EP0695000A2 is proposed as one supporting multi-circuit applications. However, in the case of using two flat cables, a lead block needs to be connected to each of the flat cables. Such a connecting operation involves a high-precision positioning process. This raises the problem that a process of manufacturing an entire rotary connector is very complex.